Organelles functions

In addition to the main DNA associated with the cell or the virus, informational DNA is found in special organelles, such as chloroplasts and mitochondria. This DNA carries genes whose products are exclusively associated with organelle function. 

Fig. 10.2. The phylogenetic distribution of mitochondrion-related organelles in eukaryotes. Organelle function is indicated as Hhydrogenosome, M mitosome or unknown...

Wei ML. 2006. Hermansky-Pudlak syndrome A disease of protein trafficking and organelle function. Pigment Cell Res 19 19-42. 

The level of free calcium in the cytosol is affected by multiple mechanisms of active and passive transport. These are summarized in Figure 6.1. While the level of calcium in the cytosol varies in time, it is always much lower than in the extracellular space, or than in the mitochondria and ER. These two organelles function as intracellular buffers or reservoirs of calcium. Accordingly, calcium transport systems operating in both directions exist not only at the cytoplasmic membrane but also at the mitochondrial (iimer) membrane and the ER. 

Both uteroferrin and bovine purple spleen acid phosphatase are competent to catalyze production of hydroxyl radical in vitro when superoxide anion is present . The generation of hydroxyl radical probably entails a Fenton-like reaction sequence dependent upon the easily reducible iron atom of the solvent-accessible binuclear cluster. No evidence is available to suggest that this reaction also occurs in vivo. However, the high mannose content of uteroferrin promotes uptake of the protein by reticuloendothehal cells of the fetal liver, ultimately directing the protein to lysosomes. Since these multifunctional organelles function in antimicrobial defense, it may be that the redox properties of uteroferrin are also exploited by the fetus in guarding against infection. 

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